In my 6502 based computer im implemented commodore bus port, thinking of future support of 1541 drive or its modern SD card based equivalent. It isn't direct copy of commodore circuit because I replaced PIA chip with Intel 8255 parallel port, so I am aware that I will have to rewrite low level I/O ...

Some time ago I've build simple 6502 based computer. At this point it is able to run EhBasic. Unfortunately it is not fully usable without working LOAD/SAVE functionality.
I am looking for some tested functionality. For now I'll be fully satisfied by loading (and saving) Motorola S19 files through ...

Ok, I am back here to report that computer is mostly working now. There is TMS9918 CRT controller and AT keyboard, serving as main I/O devices. Programs can be loaded with RS282, from S19 files.
I still wasn't able to move Basic to EPROM unfortunately. But it runs some 1970's text based games, like ...

* Microsoft BASIC for the Altair 680

Unfortunately as fr I know there are no sources available. Making it run on my hardware will be tricky and above my skill I am affraid...


* Robert Uiterwyk's 4K and 8K BASIC for the SWTPC 6800. I think the MicroBASIC you have is the 4K version. The source ...

Ok, as for now:
1) I was able to port SMITHBUG monitor to run with my hardware.
2) I was able to use S19 file loader to load software to RAM.
3) I was able to port TSC MicroBasic and run it from RAM.
4) Unfortunately (despite info from comments) this interpreter turned out not to be ROM friendly. It ...

Ok. After taking closer look at this code I can only conclude that it was designed to run on top of some Monitor software.
There are hard-coded memory addresses in the code that doesn't appear to point at some I/O devices, but rather ROM/RAM locations.
For example:


PFILBG equ $A002
PFILEN equ ...

I have been told that this topic may be violating rules of this forum, because it is only about 6502. In my opinion 6800 is related to the MOS CPU (shared peripherals like ACIA or PIA, identical bus, very similar assembly language) but I do not want to violate any rules. So if this subject is ...

It seems there are some tiny basic interpreters around for the 6800... and some have available source as well:

https://deramp.com/swtpc.com/NewsLetter1/MicroBasic.htm

https://www.corshamtech.com/wp-content/uploads/2021/01/MicroBas.zip

Thanks. I tried to assemble this interpreter with AS02 ...

While building my homemade 6502 computer, I designed twin device based on Motorola MC6802 CPU. Designing hardware part was quite trivial task as both processors share many similarities. I was also able to relatively simply translate I/O routines to 6800 assembly. So at this point I can read keyboard ...

At the risk of encouraging you to write another 16KB of code, I'd encourage you to put a well known filesystem on the card - namely entry level FAT.

The main problem is that I didn't design my hardware with such features in mind, so there is not enough of EPROM to fit all that code. I just use ...

I am relatively close to finish my project of 6502 based computer. Recently I was able to make it run CRT screen with TMS9918 chip and PC AT keyboard with 8242 chip. Now it is nearly fully functional EhBasic computer. Now I just need some solution to save and load programs.
There is CF card socket ...

This is not entirely 6502 related topic but I know this chips is quite popular among people designing own 6502 systems, so maybe I will be able to find some help here.
Some time ago I used TMS9918 in my 6502 computer, basing my design on this schematic to use it with modern single SRAM memory chip ...

I am looking for some esy way to divide 16bit variable by 40. Variable is used to point to the test cursor location in VRAM memory. Screen size is 24x40 so I need divide cursor value by 40 do determine number of current line. Cursor value will never exceed 960, so result will always be 1 byte number ...

Thanks. It works now. I suspected it must have been something trivial, I was unable to notice.

I returned to one of my old projects - homemade computer with 6502 and TMS9918 video controller.
Computer itself works with EhBasic, now I am going to write some code to add the TMS9918 support. I already done that with my other project utilizing 8080 CPU, so it is tested design. I also have 8080 ...